An IC socket having a plurality of terminals to make contact or engage with the leads of an IC package is used in carrying out a variety of tests including a burn-in test. There are a variety of IC sockets such as shown in Unexamined Patent Publication Nos. 9-266024, 10-50441, 11-54233 and other publications. Such an IC socket comprises a socket body having a seat surface formed therein, on which seat surface an IC package can be put, a plurality of terminals aligned in confronting relation and mounted in the socket body, each terminal has a contact portion to engage with a selected lead of the IC package, and an actuator member for displacing the contact portions of the terminals between the withdrawing position in which the contact portions of the terminals are apart from the seat surface of the socket body and the advancing position in which the contact portions of the terminals are so close to the seat surface of the socket body as to permit the contact portions to engage with the leads of the IC package.
Referring to FIG. 9, in a conventional IC socket a socket body 102 has a seat surface 103 formed therein, on which seat surface 103 an IC package 101 can be put. A plurality of terminals 105 are arranged in confronting relation to be mounted in the socket body 102. Each terminal 105 has a contact portion 107 to engage with a selected lead 106 of an IC package 101. A cover-like actuator member 108 is put on the socket body 102 for displacing the contact portions 107 of the terminals 105 between the withdrawing position in which the contact portions 107 of the terminals 105 are apart from the seat surface 103 of the socket body 102 and the advancing position in which the contact portions 107 of the terminals 105 are so close to the seat surface 103 of the socket body 102 as to permit the contact portions 107 to make contact or engage with the leads 106 of the IC package 101.
The socket body 102 has an IC package compartment formed therein. The seat surface 103 is formed in the compartment, which is sized to accommodate the largest possible IC package 101. As a consequence there may appear a gap between either longitudinal side of the IC package and the confronting longitudinal side wall of the compartment when an IC package of standard size or minimum allowance, and such gap is a cause for making incomplete terminal-and-lead contact in putting the IC package in the compartment.
As seen from FIG. 9, the IC package is so displaced rightward as to allow the left leads 106 of the IC package to leave apart from the contact portions 107 of the left terminals, thus allowing the IC package 101 to incline relative to the seat surface 103. Referring to FIG. 10(a), the IC package is put closer to the left longitudinal side than the right longitudinal side of the compartment. In this position each right lead 106 is pushed against the contact portion 107 of the counter terminal so forcedly that the lead 106 may be deformed more or less, or that incomplete wiping or unstable contact may be caused. On the contrary the left lead 106 of the IC package is almost apart from the contact portion 107 of the counter terminal, thereby causing incomplete contact between the lead 106 and the terminal 107, as seen from FIG. 10(b).